The present invention relates to timers and, in particular, to timers used to interrupt the power to a smoke detector for a predetermined interval.
It is known to use a timer in connection with an alarm system that can detect smoke. This known timer determines whether the sensed condition persists for a minimum duration before sounding an alarm. A disadvantage with this system is that it does employ a manual override and therefore cannot adequately handle smoky conditions that may persist for a relatively long time but which are not dangerous. For example, during its use smoke may persist in a kitchen and timed alarms according to the prior art will be triggered by this non-dangerous smoky condition. It is also known to use a smoke detector to actuate a fan for a predetermined interval of time. Of course, this known system will respond to all smoky conditions, even relatively brief ones.
Also known is a burglar alarm which has a manual disabling switch which, when actuated, prevents the burglar alarm from sounding for a predetermined interval, allowing an occupant to enter or leave a protected area without sounding the alarm. However, these known systems have not been connected to smoke detectors and therefore have not operated with appropriately sized delays or with appropriate circuitry for disabling a smoke detector.
Accordingly, there is a need for a manually operable timer for disabling a smoke detector for a predetermined interval when non-dangerous smoke may be present.